Transport measurements normally provide a macroscopic, averaged view of the sample so that disorder
prevents the observation of fragile interaction-induced states. Here, we demonstrate that transconductance
fluctuations in a graphene field effect transistor reflect charge localization phenomena on the nanometer
scale due to the formation of a dot network which forms near incompressible quantum states. These
fluctuations give access to fragile broken symmetry and fractional quantum Hall states even though these
states remain hidden in conventional magnetotransport quantities.